1. Field of the Invention
The invention herein relates to a wound dressing product, combining both a traditional dressing including a mounted absorbent material on a film backing and a hydrophobic fabric attached thereto, facing towards the wound and being capable of binding unwanted micro organisms.
2. Description of the Related Art
The problem in healing of wounds associated with bacterial loads is for example tissue damage by release of toxins and enzymes, and possible spread of infections to the blood stream. Studies have shown that high tissue counts of microorganisms delay wound healing.
Numerous studies during the last few decades have also shown that bacteria, such as Staphylococcus aureus and Group A streptococci, both common wound pathogens, and the yeast Candida albicans commonly express profound cell surface hydrophobicity. Several structures which render the cell surface hydrophobic have been defined, like the fimbriae of E. coli which mediate adhesion to the intestinal wall, proteins on C. albicans which has been called “hydrophobins”, and lipoteichoic acid in the cell wall of Gram-positive bacteria.
According to the hydrophobic principle of the laws of nature, a system will always struggle towards lowest possible energy consumption. When two water repellent molecules come into collision with each other they will increase the entropy and create disorder. The water molecules that surround the two hydrophobic molecules will force them together by hydrogen bonds between the water molecules although there is no force of attraction between the hydrophobic interaction, and will expel water molecules.
The initial step of infections of the skin and mucosal surfaces is microbial adhesion to wounded tissues. Several microbial components that adhesively bind to specific receptors have been identified, like fimbriae of Gram-negative enteric bacteria. Initial adhesion can be mediated by hydrophobic interactions between microbes and host tissue structures, and also by charge interactions. Binding of extra cellular matrix and serum proteins, like fibronectin, collagen and fibrinogen may further enhance colonization of deeper wound tissue.
In wound treatment, after tissue colonization wound microbes multiply, cause tissue damage by release of toxins and enzymes, and even spread to the blood stream. The human body has multiple defense mechanisms of the innate defense system. Also specific antibodies directed against the colonizing microorganism may be active to decrease the number of microorganisms. Numerous studies have shown that high tissue counts of microorganisms delay wound healing. On the other hand, small numbers of bacteria were shown to enhance the wound healing process in rodents by stimulating production of collagen-hydroxyproline.
Conventional treatment of wounds consists of mechanical cleansing with water, buffer solutions or disinfectants to remove bacteria and debris. This is of importance since debris hampers wound healing. The use of oxidizing agents (for example iodine tincture) or antiseptics (for example ointments comprising silver sulphadiazine) have been known for a long time. A number of disadvantages to these methods can be mentioned. For example, bacteria which have died remain in the wound, and wounds cannot be cleaned to remove the active compound reliably after the application, since it spreads in the entire wound. If these active compounds occur freely in the wound, they can also attack cells and substances in the wound fluid which promote wound healing.
Another method of wound treatment is the use of local antibiotics. Microbiologists disapprove of the use of local antibiotics since this is known to induce antibiotic resistance. Also in order to protect an already cleaned wound, including wounds from surgical cuts, various kinds of Band-Aid's, surgical tapes and dressings and the like have been used. Various kinds of cleaning and anti-microbial compounds added to such products been added or suggested for more long time effects.
What characterizes the related art in the field of the invention is that patented inventions are most often various fibrous materials and pads with added antimicrobial substances to be used with a separate bandage or fastened over wounds, using for example, surgical tape or various dressings. The invention for which patent protection is sought is a method of making an improved wound dressing product, combining both a traditional dressing with a mounted absorbent material plus a hydrophobic fabric which is capable of binding unwanted microorganisms and is attached to the absorbent material and placed towards the wound.
Products containing folded pads of bacteria-binding fabric and absorbing fabric, to be held together and on a wound by a separate bandage or tape, already exist in the market. However, not previously known are the products of the present invention in which an absorbent material is bonded to a hydrophobic material, such as a fiber, using a specially developed technique, allowing for transfer of liquids without separating the bond. In the invention herein this is combined with a backing (cover) which is visually transparent, semi-permeable and self-adhesive.
There are several known inventions relating to the use of antimicrobial substances and materials. One such example is the U.S. Pat. No. 6,369,289, which discloses the use of a cellulosic bandage in a method for covering an open wound by contacting the wound with the bandage having a calculated amount of antimicrobial agent. The disclosure of this patent and all other patents referred to herein is incorporate herein by reference. U.S. Pat. No. 4,655,756, relates to a non-woven material treated with a linear polymeric biguanide having a defined formula, or a mixture of, e.g., polyhexamethylene biguanide (PHMB).
Other types of antimicrobial agents are also known. For example, U.S. Pat. No. 5,707,736 discloses a dry, disposable, polymeric product having sustained-release antimicrobial activity that is formed from a polymeric material having an amine salt antimicrobial agent incorporated therein. The polymeric material may be in the form of fibers, sheets, films, and other stable woven, nonwoven and knitted materials. The antimicrobial agents include, e.g., chlorhexidine gluconate and chlorhexidine hydrochloride. Several similar uses of dressings combining antimicrobial compounds are known.
Other components of the invention, such as various kinds of adhesives, are also known as components of medical dressings. One such surgical dressing is described in U.S. Pat. No. 4,643,180, wherein the dressing comprises a sheet of polymeric film coated on one side with a water based adhesive of defined thickness which includes an antimicrobial agent deposited on the body-facing surface of the adhesive.
U.S. Pat. No. 4,643,181 also describes a surgical dressing and a process for making a surgical dressing. The dressing comprises a substrate coated on one surface with a solvent-based skin contact adhesive of defined thickness, the adhesive having distributed therein particles of antimicrobial substances.
U.S. Pat. No. 4,678,704 describes an impregnated fabric material comprising a fabric substrate to which has been applied an active cationic impregnant along with an anionic indicator dye in combination with a further cationic component, wherein the dye bonds to the further cationic component more readily than to the substrate and the further cationic component competes with the impregnant for bonding to the dye. The cationic impregnant may be a polymeric biguanide.
U.S. Pat. No. 5,098,417 relates to a wound dressing for systemic administration of a physiologically- or biologically-active agent by controlled release of the agent into such wound. The wound dressing comprises a substrate in the form of a fabric or cloth, at least a portion of which is cellulosic, which has been chemically modified to convert hydroxyl groups in the cellulosic portion to ionic-adsorbing sites, an ionic form of a physiologically- or biologically-active agent (which includes antibacterial agents) adsorbed in the substrate. The ionic bonds hold the agent temporarily to the substrate for controlled release therefrom in proportion to the amount of exudate in contact with the substrate and are formed by adsorbing the agent on the substrate at room temperature. The ionic bonds are disassociated upon contact with body exudate from wounds thereby to release the physiologically- or biologically-active agent in an amount in proportion to the amount of exudate in contact with the substrate.
U.S. Pat. No. 5,498,416 relates to a process for protection of prostheses, implants and/or catheters, and other temporary or permanent implantable materials against bacterial colonization and infection. An infection-resistant device is disclosed that is capable of progressively releasing in aqueous medium an amount of an antibacterial substance fixed to the device, the amount being effective to prevent bacterial contamination of the device. Devices are described to include urinary catheters, probes, vascular and intraarterial catheters, cardiacal valvular prostheses, arterial prostheses, cardiac simulators, orthopedic prostheses, ocular or dental implants, shunts that are connecting two segments of the circulatory system, and suture thread.
U.S. Pat. No. 5,700,742 relates to a method of treating a textile material to inhibit microbial growth, which comprises applying to the textile material an oligo or polymeric biguanide or salt thereof with an inorganic acid or an organic acid having a pK value above 4.5 followed by a strong organic acid having a pK value below 4.5 and free from any aliphatic or oxyalkylene chain containing 12 or more carbon atoms. A textile material treated in accordance with the claimed method is also disclosed.
U.S. Pat. No. 5,856,248 relates to cellulose fibers and products comprising cellulose fibers treated to absorb body secretions while substantially decreasing microbial growth, the fibers being chemically modified in a two-stage process comprising a first stage treatment with a water soluble salt of a transition metal and an alkali and a second stage treatment with a solution of a bisbiguanide compound, thereby forming a bond between the cellulose fibers, the transition metal and the compound. The process may utilize a rinsing step to neutral pH between the two aforementioned stages.
U.S. Pat. No. 5,817,325 relates to an article of manufacture having disposed on a surface thereof a contact-killing, non-leaching antimicrobial coating which kills microorganisms upon contact. The coating comprises an organic polycationic polymer matrix immobilized on the surface having bound or complexed thereto a surface-accessible antimicrobial metallic material such that the antimicrobial material does not release biocidal amounts of elutables into the surrounding environment.
Other patents relate to the so called SORBACT® products, which are folded dressing compositions including a hydrophobic fabric and a hydrophilic, liquid-absorbing material. U.S. Pat. No. 4,617,326 describes this principle. It has shown to be very difficult to adhere a strongly hydrophobic layer to hydrophilic liquid absorbent layers, and hence products made according to U.S. Pat. No. 4,617,326 have so far only been possible to manufacture by means of folding a separate layer in and around the hydrophilic absorbent layer and hydrophobic layer in order to keep the layers together. This is an important drawback, limiting the design and production of such wound pads.
Further, U.S. Pat. No. 6,160,196 relates to the same principle but adds thereto an antimicrobial active compound which is adapted to prevent infections from the outside of the pad, the antimicrobial compound is not be released into the wound. U.S. Pat. No. 4,211,227 discloses a non-woven surgical sponge material comprising a layered fabric having an inner core or a substantially hydrophilic material disposed adjacent at least one outer or surface layer, or between a pair of outer layers, of a substantially hydrophobic material. The sponge material is bonded by passing the material through rolls engraved in a pattern of lands and grooves such that a repeating pattern of three degrees of compression are imposed on the material. However, the so produced sponge is not using a hydrophobic material binding bacteria to any larger extent, nor does it have any backing which is visually transparent, semi-permeable and self-adhesive.
Further, there are several wound dressing products on the market containing absorbent pads, but without any anti microbial compounds or microbial binding materials, such products are Tegaderm® and Tegaderm® IV by 3M, (St. Paul, Minn. 55144-1000, U.S.A.) and OpSite Post-Op by Smith&Nephew (Memphis, Tenn. 38116, U.S.A.).
U.S. Pat. No. 5,380,294 discloses a vein catheter dressing with a supportive and adhesive foil combined with a liquid absorbing pad.
U.S. Pat. Nos. 4,275,721 and 5,380,294 describes vein catheter dressings with a centrally placed liquid absorbent pad located on an adhesive foil layer. The adhesive is covered with two separate release layers which is to be removed before application of the dressing. The dressings have a slit which departs from one end of the dressing to a short distance from the absorbent pad (U.S. Pat. No. 4,275,721), or up to or into the pad (U.S. Pat. No. 5,380,294).
U.S. Pat. No. 5,380,294 is distinguished from U.S. Pat. No. 4,275,721 by the addition of a transparent layer on and around the absorbent pad. The purpose of the transparent layer is to be able to inspect the incision place and the surrounding area in order to detect an eventual infection. The location of the transparent layer in U.S. Pat. No. 5,380,294 is limited to only the side of the pad opposite the slit.
Utilizing the Sorbact principle discussed above, products such as the Sorbact pad consist of folded acetate gauze and cotton gauze treated with the fatty acid ester DACC (dialkyl carbamoyl chloride). This provides Sorbact pads with a strong hydrophobic property. When the Sorbact pad gets in contact with pathogenic microorganisms in the wound surface, the microorganisms adhere to the pad through hydrophobic interaction. The method is based on the principle that two hydrophobic surfaces bind to each other, when getting in physical contact. The Sorbact pad consists of two components. The first component has one or more liquid permeable layers of a hydrophobic, bacteria adsorbing, physiologically innocuous material containing a woven or nonwoven hydrophilic fabric. The fabric has been rendered hydrophobic by chemical treatment with a compound containing hydrophobic groups. The second component consists of one or more layers of a hydrophilic, liquid adsorbing, physiologically innocuous material. The hydrophilic liquid absorbing material effects a liquid flow by suction of exudate from the wound. If the microorganisms exhibit hydrophobic surface structures they will accompany this flow of liquid and come in contact with the hydrophobic component and bind.
Even if the traditional Sorbact pad product solves an important problem of reducing the number of microorganisms in a wound without using chemicals or antibiotics, it has several disadvantages when used as a wound dressing. Firstly, it will need to be attached to the wound surface with a bandage using such materials as a cotton gauze wrap, surgical tape and the like. This means that there are several steps and products involved for the user to apply the Sorbact pad, which among other things leads to increased costs and time to handle. Further, such a combined bandage will be sensitive to liquids, such as water, moisture, dirt, microorganisms etc. from the outside, being possible to penetrate the bandage. Further, it has been showed that a good contact between the wound and the hydrophobic fabric is important for an efficient attachment/binding of the unwanted microbes of the wound. Depending on the location on the body of the wound, this is not always easy to achieve with the loose pad and a bandage. Further, it is difficult to inspect the status of the wound in terms of inflammation etc. through a bandage.
Now, therefore the invention herein was made to address the above problems.
It is an object of the invention herein to provide a product ideal for the treatment of wounds and a method of making this product. It is a further object of the invention to provide a product that protects the wound, absorbs exudate and reduces the number of pathogenic microorganisms, without using antimicrobial substances. It is a further object of the invention to provide a product that may be made visually transparent, as well as being semi-permeable and self-adhesive, allowing passage of oxygen and moisture and inspection of the surrounding skin at the same times as the product binds existing pathogens and prevents the entry of new pathogens from the outside.